Optical module, method of manufacturing the optical module, and data communication system including the optical module

ABSTRACT

An optical module includes a fiber array, a laser diode array and a photodiode array. The fiber array has optical fibers which are divided to a transmitter group and a receiver group. The laser diode array has laser diodes which are grouped in a transmitter group. The photodiode array has photodiodes which are divided to a monitor group and a receiver group. The laser diode array is provided between the fiber array and the photodiode array. Each optical fiber of the transmitter group, each laser diode of the transmitter group and each photodiode of the monitor group are optically aligned, respectively. Each optical fiber of the receiver group is optically aligned with each photodiode of the receiver group, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. Ser. No. 11/839,953, filed Aug. 16, 2007,which is a divisional of U.S. Ser. No. 11/046,875, filed Feb. 1, 2005(Now, U.S. Pat. No. 7,338,218). The entire contents of that applicationare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical module, a method ofmanufacturing the optical module, and a data communication systemincluding the optical module.

2. Discussion of the Background

United States Patent Application Publication No. US2002/0114590 A1discloses an optical interface for a 4-channel opto-electronictransmitter-receiver module. The optical interface for the 4-channelopto-electronic transmitter-receiver module includes a module housing, atransmitter chip, a receiver chip and an adapter unit. The modulehousing includes at least one housing wall, and is provided with a wallopening in the housing wall. The transmitter chip includes a 4-channellaser diode array, and the receiver chip includes a 4-channelphotodetector array. The transmitter chip and the receiver chip aremounted in the wall opening. The adapter unit includes eight opticalfibers, each of which has a proximal fiber end and an opposite fiberend.

Proximal fiber ends of the optical fibers are grouped in two fiber endarrays. Each of the two fiber end arrays is supported in opticalalignment with a corresponding one of the 4-channel laser diode arrayand the 4-channel photodetector array. Each of the two fiber end arraysincludes four fiber ends evenly spaced apart from each other. The twofiber end arrays are spaced apart from each other by a distance greaterthan spacing between adjacent optical fibers in each of the two fiberend arrays.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an optical moduleincludes a fiber array, a laser diode array and a photodiode array. Thefiber array has optical fibers which are divided to a transmitter groupand a receiver group. The laser diode array has laser diodes which aregrouped in a transmitter group. The photodiode array has photodiodeswhich are divided to a monitor group and a receiver group. The laserdiode array is provided between the fiber array and the photodiode arraysuch that each end surface of the optical fibers of the transmittergroup faces each laser diode of the transmitter group. Each opticalfiber of the transmitter group, each laser diode of the transmittergroup and each photodiode of the monitor group are optically aligned,respectively. Each optical fiber of the receiver group is opticallyaligned with each photodiode of the receiver group, respectively.

According to another aspect of the present invention, a method ofmanufacturing an optical module includes positioning a laser diodesubmount, which is provided with a laser diode array, onto a bridge,which is provided with a terminal block, and connecting one end of alaser diode lead wire to the laser diode array and another end of thelaser diode lead wire to a bonding pad of the terminal block. In thismethod, each optical fiber of a transmitter group of a fiber array isoptically aligned with each corresponding laser diode of a transmittergroup. Then, the fiber array is connected to the laser diode submount.Each optical fiber of a transmitter group and a receiver group of amechanical transfer ferrule is optically aligned with each correspondingphotodiode of a monitor group and a receiver group of a photodiode arraywhich is provided on a photodiode submount. Then, the mechanicaltransfer ferrule is connected to the photodiode submount. The fiberarray, which is connected with the laser diode submount provided withthe laser diode array, is connected with the mechanical transferferrule, which is connected with the photodiode submount provided withthe photodiode array, using a guide pin such that each optical fiber ofthe transmitter group of the fiber array, each laser diode of thetransmitter group, each optical fiber of the transmitter group of themechanical transfer ferrule and each photodiode of the monitor group areoptically aligned, respectively, and such that each optical fiber of areceiver group of the fiber array, each optical fiber of the receivergroup of the mechanical transfer ferrule and each photodiode of thereceiver group are optically aligned, respectively.

According to yet another aspect of the present invention, a datacommunication system includes an optical module which has a fiber array,a laser diode array and a photodiode array. The fiber array has opticalfibers which are divided to a transmitter group and a receiver group.The laser diode array has laser diodes which are grouped in at least atransmitter group. The photodiode array has plural photodiodes which aredivided to a monitor group and a receiver group. The laser diode arrayis provided between the fiber array and the photodiode array such thateach end surface of the optical fibers of the transmitter group faceseach laser diode of the transmitter group. Each optical fiber of thetransmitter group, each laser diode of the transmitter group and eachphotodiode of the monitor group are optically aligned, respectively.Each optical fiber of the receiver group is optically aligned with eachphotodiode of the receiver group, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a top plan view of an optical module according to anembodiment of the present invention;

FIG. 2 is a cross sectional view of the optical module cut along theline II-II of FIG. 1;

FIG. 3 is a cross sectional view of the optical module cut along theline III-III of FIG. 1;

FIG. 4 is a top plan view of an optical module according to anembodiment of the present invention;

FIG. 5 is a cross sectional view of the optical module cut along theline V-V of FIG. 4;

FIG. 6 is an end view of the optical module in FIG. 4;

FIG. 7 is a top plan view of an optical module according to anembodiment of the present invention;

FIG. 8 is a cross sectional view of the optical module cut along theline VIII-VIII of FIG. 7;

FIG. 9 is a top plan view of an optical module according to anembodiment of the present invention;

FIG. 10 is a cross sectional view of the optical module cut along theline X-X of FIG. 9;

FIG. 11 is showing a method of manufacturing an optical module accordingto the present invention;

FIG. 12 is a side view of an optical module according to an embodimentof the present invention; and

FIG. 13 is showing a data communication system according to anembodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

FIGS. 1-3 show an optical module according to an embodiment of thepresent invention. Referring to FIGS. 1-3, the optical module 2includes, a multi-channel, for example, 8-channel fiber array 4, amulti-channel, for example, 4-channel laser diode array 6, a laser diodesubmount 8, a multi-channel, for example, 8-channel photodiode array 10,and a photodiode submount 14.

The laser diode array 6 is bonded on the laser diode submount 8. Thephotodiode array 10 is bonded to the photodiode submount 14. The fiberarray 4 and the photodiode submount 14 are connected to sandwich thelaser diode submount 8. A spacer 16 is provided between the photodiodesubmount 14 and the laser diode submount 8 to tilt the photodiode array,with a predetermined angle, away from the fiber array 4 to reduceunwanted back reflection, caused by the photodiode array 10, intooptical fibers of the fiber array. The spacer 16 has a thickness of, forexample, about 200 μm and is made of, for example, a resin material. Thephrase “about 200 μm” includes reasonable measuring margins of erroraccepted by persons skilled in the art. This use of “about” isapplicable throughout this specification.

The fiber array 4 includes eight optical fibers 4 a-4 h extendingthrough the fiber array 4. The fiber array 4 is divided to a transmittergroup which includes first to fourth optical fibers 4 a-4 d, and areceiver group which includes fifth to eighth optical fibers 4 e-4 h.The laser diode array 6 includes first to fourth laser diodes 6 a-6 dwhich are grouped together as a transmitter group. The photodiode array10 includes eight photodiodes which are divided to a monitor groupincluding first to fourth photodiodes 10 a-10 d and a receiver groupincluding fifth to eighth photodiodes 10 e-10 h.

The fiber array 4, the laser diode array 6, and the photodiode array 10are arranged such that the first to fourth optical fibers 4 a-4 d of thetransmitter group, the first to fourth laser diodes 6 a-6 d of thetransmitter group and the first to fourth photodiodes 10 a-10 d of themonitor group are optically aligned, respectively, and the fifth toeighth optical fibers 4 e-4 h of the receiver group and the fifth toeighth photodiodes 10 e-10 h of the receiver group are opticallyaligned, respectively.

A distance between each of end surfaces of the optical fibers 4 a-4 d ofthe transmitter group and each corresponding one of the laser diodes 6a-6 d of the transmitter group is at least about 10 μm and at most about50 μm, preferably at least about 20 μm and at most about 30 μm. Adistance between each of the laser diodes 6 a-6 d of the transmittergroup and each corresponding one of the photodiodes 10 a-10 d of themonitor group is at least about 20 μm at most about 100 μm. A distancebetween each of end surfaces of the optical fibers 4 e-4 h of thereceiver group and each corresponding one of the photodiodes 10 e-10 hof the receiver group is at least about 170 μm and at most about 500 μm.

According to this embodiment of the present invention, the eight opticalfibers 4 a-4 h, the four laser diodes 6 a-6 d and the eight photodiodes10 a-10 h have substantially equal pitches which are at least about 125μm. In addition, a combined number of the optical fibers of thetransmitter group and the receiver group of the fiber array 4 is eight,which is equal to a combined number of the photodiodes of the monitorgroup and the receiver group, and twice a number of the laser diodes ofthe transmitter group. Moreover, the eight optical fibers 4 a-4 h of thefiber array are equally divided to the transmitter group and thereceiver group, and the eight photodiodes 10 a-10 h are equally dividedto the transmitter group and the receiver group.

However, the pitches between the optical fibers 4 a-4 h, the laserdiodes 6 a-6 d and the photodiodes 10 a-10 h may be arranged such that,for example, a pitch within one group of the fiber array 4 is differentfrom a pitch within another group of the fiber array 4, or a pitchbetween the transmitter group and the receiver group of the fiber array4 is different from a pitch within the transmitter group and thereceiver group of the fiber array.

Further, the fiber array 4 may have any plural number of optical fibersand may be divided to more groups than the transmitter group and thereceiver group. The photodiode array 10 may have any plural number ofphotodiodes and may be divided to more groups than the monitor group andthe receiver group. The optical fibers and the photodiodes may bedivided to plural groups unevenly, as long as each optical fiber of thetransmitter group, each corresponding laser diode of the transmittergroup and each corresponding photodiode of the monitor group can beoptically aligned, respectively, and as long as each optical fiber ofthe receiver group can be optically aligned with each correspondingphotodiode of the receiver group. A group or groups other than thetransmitter group and the receiver group of the fiber array 4 may haveone or more functions different from either or both the transmittergroup and the receiver group of the fiber array 4, and a group or groupsother than the monitor group and the receiver group of the photodiodearray 10 may have one or more 3 functions different from either or boththe monitor group and the receiver group of the photodiode array 10.

Similarly, the laser diode array 6 may have one laser diode or anyplural number of laser diodes. The laser diode array 6 may be divided tomore groups than the transmitter group, and may be divided to pluralgroups unevenly, as long as each optical fiber of the transmitter group,each corresponding laser diode of the transmitter group and eachcorresponding photodiode of the monitor group can be optically aligned,respectively. A group or groups of the laser diode array 6 other thanthe transmitter group may have one or more functions different from thetransmitter group of the laser diode array 6.

Moreover, according to this embodiment of the present invention, thetransmitter group and the receiver group of the fiber array 4 areadjacent to each other, and the monitor group and the receiver group ofthe photodiode array 10 are adjacent to each other. In addition, thefiber array 4 and the photodiode array 10 each have a single tierincluding a first part and a second part. In the fiber array 4, theoptical fibers 4 a-4 d of the transmitter group are in the first part,and the optical fibers 4 e-4 h of the receiver group are in the secondpart. In the photodiode array 10, the photodiodes 10 a-10 d of themonitor group are in the first part, and the photodiodes 10 e-10 h ofthe receiver group are in the second part.

However, one or more optical fibers or one or more different componentsof the optical module may be provided between the transmitter group andthe receiver group of the fiber array 4. Consequently, the photodiodearray 10 may have one or more photodiodes or one or more differentcomponents of the optical module between the monitor group and thereceiver group. The monitor group and the receiver group of thephotodiode array 10 may be simply spaced a part in order to be inoptical alignment with the fiber array 4. Further, the first part of thefiber array 4 and the first part of the photodiode array 10 may beeither side of the second part of the fiber array 4 and the second partof the photodiode array 10, as long as the transmitter group and thereceiver group of the fiber array 4 are optically aligned with themonitor group and the receiver group of the photodiode array 10,respectively.

According to this embodiment of the present invention, a transmittercircuit 18 is connected to the laser diode 6 a-6 d of the transmittergroup and to the photodiodes 10 a-10 d of the monitor group. A receivercircuit 20 is connected to the photodiodes 10 e-10 h of the receivergroup. The transmitter circuit 18 controls the laser diodes 6 a-6 d toemit optical signals according to electrical signals to be transmittedbeing input to the transmit circuit 18 via signal input lines 18 a-18 d.The photodiodes 10 a-10 d of the monitor group receive optical signalsemitted from the laser diodes 6 a-6 d of the transmitter group, andoutput received optical signals to the transmitter circuit 18 to performfeed back control of the laser diodes 6 a-6 d. The photodiodes 10 e-10 hof the receiver group receive optical signals transmitted via theoptical fibers 4 e-4 h of the receiver group, convert received opticalsignals to electrical signals, and output the electrical signals to thereceiver circuit 20.

According to this embodiment of the present invention, the pitches ofthe optical fibers 4 a-4 h of the fiber array 4, the laser diodes 6 a-6d of the laser diode array 6 and the photodiodes 10 a-10 h of thephotodiode array 10 are substantially equal. In addition, on a singlesubstrate of the photodiode array 10, the photodiodes 10 a-10 d of themonitor group and the photodiodes 10 e-10 h of the receiver group can bepositioned together, and perform functions of both independentmonitoring of the optical output power of each of the laser diodes 6 a-6d of the transmitter group, and receiving optical signals from theoptical fibers 4 e-4 h of the receiver group.

As a result, for transmitting and receiving optical signals, the opticalmodule according to this embodiment of the present invention canincrease, within limited space, a number of channels which are providedwith optical output power monitors. Moreover, according to thisembodiment of the present invention, structures of an optical module canbe simplified, and manufacturing cost of an optical module can bereduced.

FIGS. 4-6 show an optical module according to an embodiment of thepresent invention which includes a two tiered multi-channel fiber arrayand a two tiered multi-channel photodiode array. Referring to FIGS. 4-6,the optical module 32 includes, a two tiered multi-channel, for example,16-channel fiber array 34, a multi-channel, for example, 8-channel laserdiode array 36, a laser diode submount 38, a two tiered multi-channel,for example, 16-channel photodiode array 40, and a photodiode submount44.

The two tiered fiber array 34 is provided with a first tier and a secondtier. First to eighth optical fibers 34 a-34 h in the first tier are ina transmitter group, and ninth to sixteenth optical fibers 34 i-34 p inthe second tier are in a receiver group. The laser diode array 36includes first to eighth laser diodes 36 a-36 h grouped as a transmittergroup. The two tiered photodiode array 40 is provided with a first tierand a second tier. First to eighth photodiodes 40 a-40 h in the firsttier are in a monitor group, and ninth to sixteenth photodiodes 40 i-40p in the second tier are in a receiver group.

Pitches between each optical fiber of the first tier and each opticalfiber of the second tier directly above the each optical fiber of thefirst tier, for example, between an optical fiber 34 a and an opticalfiber 34 i, between each photodiode of the first tier and eachphotodiode of the second tier directly above the each photodiode of thefirst tier, between eight optical fibers of each of the transmittergroup and the receiver group of the fiber array, between eight laserdiodes of the transmitter group of the laser diode array, and betweeneight photodiodes of each of the monitor group and the receiver group ofthe photodiode array are substantially equal, and at least about 125 μm.

The fiber array 34, the laser diode array 36 and the photodiode array 40are arranged such that the first to eighth optical fibers 34 a-34 h ofthe transmitter group, the first to eighth laser diodes 36 a-36 h of thetransmitter group and the first to eighth photodiodes 40 a-40 h of themonitor group are optically aligned, respectively, and the ninth tosixteenth optical fibers 34 i-34 p of the receiver group and the ninthto sixteenth photodiodes 40 i-40 p of the receiver group are opticallyaligned, respectively. Each of the first to eighth photodiodes 40 a-40 hof the monitor group in the first tier receives optical output power ofeach of the first to eighth laser diodes 36 a-36 h of the transmittergroup, respectively, and each of the ninth to sixteenth photodiodes 40i-40 p of the receiver group in the second tier receives optical signalsfrom each of the optical fibers 34 i-34 p of the receiver group,respectively.

According to this embodiment of the present invention, the first tierand the second tier of the fiber array are in a lower tier and an uppertier, respectively, and are adjacent to each other. The first tier andthe second tier of the photodiode array are in a lower tier and an uppertier, respectively, and are adjacent to each other. However, the firsttier may be upper in relation to the second tier in the fiber array andthe photodiode array. In addition, one or more tiers of optical fibersor photodiodes, or one or more of other components of the optical modulemay be provided between the first tier and the second tier in either orboth the fiber array and the photodiode array. Further, the laser diodearray may have one or more groups in one or more tiers other than a tierof the transmitter group, as long as each optical fiber of thetransmitter group, each corresponding laser diode of the transmittergroup and each corresponding photodiode of the monitor group can beoptically aligned, respectively, and as long as each optical fiber ofthe receiver group can be optically aligned with each correspondingphotodiode of the receiver group.

Moreover, the fiber array and the photodiode array may have any pluraloptical fibers and any plural photodiodes, respectively, and may bedivided, evenly or unevenly, to plural groups in plural tiers. The laserdiode array may have one or more laser diodes, and may be grouped,evenly or unevenly, in one or more groups in one or more tiers, as longas the optical fibers of the transmitter group, the laser diodes of thetransmitter group, the photodiodes of the monitor group are opticallyaligned, respectively, and the optical fibers of the receiver group andthe photodiodes of the receiver group are optically aligned,respectively.

According to this embodiment of the present invention, the fiber arrayand the photodiode array can be arranged such that the pitches betweeneach optical fiber of the first tier and each optical fiber of thesecond tier directly above the each optical fiber of the first tier,between each photodiode of the first tier and each photodiode of thesecond tier directly above the each photodiode of the first tier,between the eight optical fibers of each of the transmitter group andthe receiver group of the fiber array, between the eight laser diodes ofthe transmitter group of the laser diode array, and between the eightphotodiodes of each of the monitor group and the receiver group of thephotodiode array are substantially equal. In addition, on a singlesubstrate of the photodiode array, the photodiodes of the monitor groupand the receiver group can be positioned adjacent to each other, andperform functions of both independent monitoring of the optical outputpower of each of the laser diodes 36 a-36 h of the transmitter group,and receiving the optical signals from the optical fibers 34 i-34 p ofthe receiver group.

As a result, the optical module according to this embodiment of thepresent invention can increase, within limited space, a number ofchannels which are provided with optical output power monitors.Moreover, according to this embodiment of the present invention,structures of an optical module can be simplified, and manufacturingcost of an optical module can be reduced.

FIGS. 7 and 8 show an optical module according to an embodiment of thepresent invention which includes a mechanical transfer ferrule.Referring to FIGS. 7-8, the optical module 62 includes, a multi-channel,for example, 8-channel fiber array 64, a multi-channel, for example,4-channel laser diode array 66, a laser diode submount 68, amulti-channel, for example, 8-channel photodiode array 70, a photodiodesubmount 74, and the mechanical transfer ferrule 80 with plural, forexample, 8 optical fibers.

The fiber array 64 and the laser diode submount 68, and the laser diodesubmount 68 and the mechanical transfer ferrule 80 are bonded to eachother to sandwich the laser diode array 66 by the fiber array 64 and themechanical transfer ferrule 80. In addition, the fiber array 64 and themechanical transfer ferrule 80 are connected by two guide pins 82 tosandwich the laser diode array 66 and the laser diode submount 68. Aspacer 76 is provided between the mechanical transfer ferrule 80 and thephotodiode submount 74 to provide space for the photodiode array 70which is bonded on the photodiode submount 74. A photodiode lead wire 88connects the photodiode array 70 to electrical circuits 90 to supplyelectrical currents and to receive electrical signals. A laser diodelead wire 86 connects the laser diode array 66 to the electricalcircuits 90 to supply electrical currents and to receive electricalsignals.

The fiber array 64 includes first to fourth optical fibers 64 a-64 d ofa transmitter group, and fifth to eighth optical fibers 64 e-64 h of areceiver group. The laser diode array 66 includes first to fourth laserdiodes 66 a-66 d of a transmitter group. The photodiode array 70includes first to fourth photodiodes 70 a-70 d of a monitor group, andfifth to eighth photodiodes 70 e-70 h of a receiver group. Themechanical transfer ferrule 80 includes first to fourth optical fibers80 a-80 d of a transmitter group and fifth to eighth optical fibers 80e-80 h of a receiver group.

The fiber array 64, the laser diode array 66, the mechanical transferferrule 80, and the photodiode array 70 are arranged such that the firstto fourth optical fibers 64 a-64 d of the transmitter group of the fiberarray, the first to fourth laser diodes 66 a-66 d of the transmittergroup, the first to fourth optical fibers 80 a-80 d of the transmittergroup of the mechanical transfer ferrule, and the first to fourthphotodiodes 70 a-70 d of the monitor group are optically aligned alongan optical axis direction of transmitter groups, respectively, and suchthat the fifth to eighth optical fibers 64 e-64 h of the receiver groupof the fiber array, the fifth to eighth optical fibers 80 e-80 h of thereceiver group of the mechanical transfer ferrule, and the fifth toeighth photodiodes 70 e-70 h of the receiver group are optically alignedalong an optical axis direction of receiver groups, respectively. Alength of the mechanical transfer ferrule 80 along each of the opticalaxis direction of transmitter groups and the optical axis direction ofreceiver groups is, for example, at least about 1 mm.

Here, each pair of the transmitter group and the receiver group of thefiber array, the monitor group and the receiver group of the photodiodearray, and the transmitter group and the receiver group of themechanical transfer ferrule are adjacent to each other within arespective pair. However, one or more groups of optical fibers or one ormore of other components of the optical module may be provided betweenthe transmitter group and the receiver group of the fiber array.Similarly, one or more groups of photodiodes or one or more of othercomponents of the optical module may be provided between the monitorgroup and the receiver group of the photodiode array, and one or moregroups of optical fibers or one or more of other components of theoptical module may be provided between the transmitter group and thereceiver group of the mechanical ferrule, as long as the optical fibersof the transmitter group of the fiber array, the laser diodes of thetransmitter group, the optical fibers of the transmitter group of themechanical ferrule and the photodiodes of the monitor group areoptically aliened, respectively, and the optical fibers of the receivergroup of the fiber array, the optical fibers of the receiver group ofthe mechanical ferrule and the photodiodes of the receiver group areoptically aligned, respectively.

According to this embodiment of the present invention, because each ofthe optical fibers of the transmitter group 80 a-80 d and the receivergroup 80 e-80 h of the mechanical transfer ferrule has a numericalaperture of at most about 0.21, the mechanical transfer ferrule 80 canreduce optical crosstalk between optical signals emitted from the laserdiodes 66 a-66 d of the transmitter group to be received by thephotodiodes 70 a-70 d of the monitor group, respectively. The mechanicaltransfer ferrule 80 can also reduce optical crosstalk between the laserdiodes 66 a-66 d of the transmitter group and the optical fibers 64 e-64h of the receiver group of the fiber array.

Moreover, because the mechanical transfer ferrule separates a pointwhere the photodiode lead wire 88 is connected to the photodiode arrayfrom a point where the laser diode lead wire 86 is connected to thelaser diode array, providing a distance of, for example, at least about1 mm, electrical crosstalk between the photodiode lead wire 88 and thelaser diode lead wire 86 can be reduced, thereby allowing the electricalcircuits 90 to accurately receive electrical signals via the photodiodelead wire 88 and the laser diode lead wire 86.

Further, because the mechanical transfer ferrule 80 and the fiber array64 are connected by the two guide pins 82, the mechanical transferferrule 80 can be precisely positioned in relation to the fiber array64, and can also increase bonding strength between the laser diodesubmount 68 and the fiber array 64. Because of the two guide pins 82,the bonding strength between the laser diode submount 68 and the fiberarray 64 can be increased to pass a temperature cycle test at −40° C.,85° C. and 500 cycles, and a high temperature and high humidity storagetest at 85° C., 85% and 5,000 hours.

As a result, the optical module according to this embodiment of thepresent invention can increase, within limited space, a number ofchannels which are provided with optical output power monitors, and canalso stabilize transmission and reception of optical signals. Inaddition, because use of the two guide pins increases the bondingstrength between the laser diode submount and the fiber array, theoptical module can be used even under an environment with either or botha high temperature and a high humidity. Moreover, structures of anoptical module can be simplified, and manufacturing cost of an opticalmodule can be reduced.

FIGS. 9 and 10 show an optical module according to an embodiment of thepresent invention which includes a shield metal. Referring to FIGS. 9and 10, the optical module 102 includes, a multi-channel, for example,8-channel fiber array 104, a multi-channel, for example, 4-channel laserdiode array 106, a laser diode submount 108, a multi-channel, forexample, 8-channel photodiode array 110, a photodiode submount 114, amechanical transfer ferrule 120 with plural, for example, 8 opticalfibers, and the shield metal 124.

The shield metal 124 is provided near a photodiode lead wire 128, bondedonto a surface of the mechanical transfer ferrule 120, and sandwiched bythe photodiode array 110 and the mechanical transfer ferrule 120. Theshield metal 124 may be between the laser diode array 106 and themechanical transfer ferrule 120. A laser diode lead wire 126 connectsthe laser diode array 106 to electrical circuits 130. The photodiodelead wire 128 connects the photodiode array 110 to the electricalcircuits 130.

According to this embodiment of the present invention, the shield metal124 prevents electrical crosstalk between the photodiode lead wire 128and the laser diode lead wire 126, which affects the photodiode leadwire 128, thereby increasing accuracy of electrical signals which theelectrical circuits 130 receive from the photodiode array 110 via thephotodiode lead wire 128. In addition, the mechanical transfer ferrule120 coated by metal or made from metal coated plastics can also preventsthe electrical crosstalk between the photodiode lead wire 128 and thelaser diode lead wire 126, thereby increasing the accuracy of theelectrical signals which the electrical circuits 130 receive from thephotodiode array 110 via the photodiode lead wire 128.

As a result, the optical module according to this embodiment of thepresent invention can increase, within limited space, a number ofchannels which are provided with optical output power monitors, and canalso stabilize transmission and reception of optical signals. Inaddition, because use of at least one guide pin to connect themechanical transfer ferrule and the fiber array increases bondingstrength between the laser diode submount and the fiber array, theoptical module can be used even under an environment with either or botha high temperature and a high humidity. Moreover, according to thisembodiment of the present invention, structures of an optical module canbe simplified, and manufacturing cost of an optical module can bereduced.

FIG. 11 shows a method of manufacturing an optical module according toan embodiment of the present invention which includes a bridge and aterminal block on the bridge. Referring to FIG. 11, the optical module142 includes, a multi-channel fiber array 144, a multi-channel laserdiode array 146, a laser diode submount 148, a multi-channel photodiodearray 150, a photodiode submount 154, a multi-channel mechanicaltransfer ferrule 160, the bridge 172 and the terminal block 174.

The bridge 172 connects with the laser diode submount 148. The laserdiode submount 148 has a thickness of at least about 150 μm and at mostabout 350 μm. The bridge 172 is provided with an opening so that opticalsignals transmitted from laser diodes of a transmitter group of thelaser diode array 146 and from optical fibers of a receiver group of thefiber array can pass through to be received by corresponding photodiodesof a monitor group and a receiver group of the photodiode array 150,without being attenuated. The terminal block 174, which is provided onthe bridge 172, has a bonding pad 176 to bond one end of a laser diodelead wire 166 to the terminal block 174. The mechanical transfer ferrule160 is connected with the bridge 172 and the photodiode array 150 to besandwiched by the bridge 172 and the photodiode array 150. The fiberarray 144, the laser diode array 146, the mechanical transfer ferrule160 and the photodiode array 150 are optically aligned, respectively.

According to this embodiment of the present invention, because the laserdiode submount 148 is provided with the bridge 172 and the terminalblock 174, the laser diode lead wire 166 can be bonded to the laserdiode array 146 without a need of a special tool, even when the laserdiode submount 148 is with a thickness of, for example, about 150 μm. Asa result, the optical module according to this embodiment of the presentinvention can reduce manufacturing cost.

In the manufacturing of the optical module according to the presentinvention, in a process A, the laser diode submount 148, on which thelaser diode array 146 is provided, is positioned on the bridge 172, onwhich the terminal block 174 is provided. Then, one end of the laserdiode lead wire 166 is bonded to the laser diode array 146 and anotherend of the laser diode lead wire 166 to the bonding pad 176 of theterminal block 174.

In a process B, each optical fiber of a transmitter group of the fiberarray 144 is optically aligned with each corresponding laser diode ofthe transmitter group of the laser diode array 146. Then, the fiberarray 144 is bonded to the laser diode submount 148 with the laser diodearray 146, which is positioned on the bridge 172 during the process A.

In a process C, each optical fiber of a transmitter group and a receivergroup of the mechanical transfer ferrule 160 is optically aligned witheach corresponding photodiode of the monitor group and the receivergroup of the photodiode array 150. Then, the mechanical transfer ferrule160 is bonded to the photodiode submount 154 with the photodiode array150.

In a process D, the mechanical transfer ferrule 160, onto which thephotodiode submount 154 is bonded during the process C, is connectedwith the fiber array 144, onto which the laser diode submount 148 isbonded during the process B, using at least one guide pin 162, such thateach optical fiber of the transmitter group of the fiber array, eachlaser diode of the transmitter group, each optical fiber of thetransmitter group of the mechanical transfer ferrule and each photodiodeof the monitor group are optically aligned, respectively, and such thateach optical fiber of the receiver group of the fiber array, eachoptical fiber of the receiver group of the mechanical transfer ferruleand each photodiode of the receiver group are optically aligned,respectively.

According to this method of manufacturing an optical module of thepresent invention, because the laser diode submount 148 is provided withthe bridge 172 and the terminal block 174, the laser diode lead wire 166can be bonded to the laser diode array 146 without a need of a specialtool, even when the laser diode submount 148 is with a thickness of, forexample, about 150 μm. As a result, the optical module according to thisembodiment of the present invention can reduce manufacturing cost.

FIG. 12 shows an optical module according to an embodiment of thepresent invention which includes a flexible cable. Referring to FIG. 12,the optical module 202 includes a multi-channel fiber array 204, amulti-channel laser diode array 206, a laser diode submount 208, amulti-channel photodiode array 210, a mechanical transfer ferrule 220,and the flexible cable 240.

The flexible cable 240, which replaces a photodiode submount, isprovided with a shield metal layer 242 on one side, and a tracephotodiode 244 on an opposite side to the side with the shield metallayer 242. The trace photodiode 244 has an opening through which opticalsignals, emitted by laser diodes of the laser diode array 206 and byoptical fibers of the fiber array 204, can pass to be received bycorresponding photodiodes of the photodiode array 210, without beingattenuated. The shield metal layer 242 of the flexible cable ispositioned so that electrical crosstalk between a laser diode lead wire226 and the trace photodiode 244 is prevented.

According to this embodiment of the present invention, the flexiblecable 240 includes functions of a photodiode submount, a spacer betweenthe laser diode array 206 and the photodiode array 210 or between thephotodiode array 210 and a shield metal, a shield metal between thelaser diode array 206 and the photodiode array 210, and a photodiodelead wire which connects the photodiode array 210 to electrical circuits230.

As a result, the optical module according to this embodiment of thepresent invention can be manufactured with fewer parts, can increasewithin limited space a number of channels which are provided withoptical output power monitors, and can also stabilize transmission andreception of optical signals. In addition, because use of at least oneguide pin to connect the mechanical transfer ferrule and the fiber arrayincreases bonding strength between the laser diode submount and thefiber array, the optical module can be used even under an environmentwith either or both a high temperature and a high humidity. Moreover,according to this embodiment of the present invention, structures of anoptical module can be simplified, and manufacturing cost of an opticalmodule can be reduced.

FIG. 13 shows a data communication system according to an embodiment ofthe present invention. Referring to FIG. 13, the data communicationsystem 300 includes at least one optical module 302, which is, forexample, an optical module shown in FIGS. 1-3. Fiber ends 350 of a fiberarray 314 of the optical module 302 are connected to fiber ends 390 of acommunication fiber array 374. Another fiber ends 392 of thecommunication fiber array 374 are connected to a data communicationmodule 362. The data communication system 300 according to thisembodiment of the present invention may include other optical modulesshown in FIGS. 4-6, FIGS. 7-8, FIGS. 9-10, FIG. 11 and FIG. 12. The datacommunication system 300 may be, for example, an intermediate opticalfiber communication system or a part of the intermediate optical fibercommunication system. A service provider of the intermediate opticalfiber communication system, which has many individual subscribers, maybe required to carry, for example, one thousand of multi-channel opticalmodules at a node of a base station of the service provider. Accordingto this embodiment of the present invention, because the optical module302 can increase, within limited space, a number of channels to transmitand receive information, a size of the data communication system 300 canbe decreased. The data communication system 300 can also be at least apart of, for example, a satellite communication system, atelecommunication system, a visual image communication system or acomputer data communication system.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. An optical module comprising: a fiber array including plural opticalfibers which are divided to at least a transmitter group and a receivergroup; a laser diode array including plural laser diodes which aregrouped in at least a transmitter group; a photodiode array includingplural photodiodes which are divided to at least a monitor group and areceiver group, the laser diode array being provided between the fiberarray and the photodiode array such that each of end surfaces of theplural optical fibers of the transmitter group faces each of the plurallaser diodes of the transmitter group, each of the plural optical fibersof the transmitter group, each of the plural laser diodes of thetransmitter group and each of the plural photodiodes of the monitorgroup being optically aligned, respectively, and each of the pluraloptical fibers of the receiver group being optically aligned with eachof the plural photodiodes of the receiver group, respectively; a laserdiode submount being provided with the laser diode array; a bridge beingprovided with the laser diode submount and being arranged to allowoptical signals, emitted from the transmitter group of the laser diodearray and from the receiver group of the fiber array, to pass throughwithout being attenuated; a terminal block having a bonding pad andbeing provided with the bridge; and a laser diode lead wire one end ofwhich is bonded to the bonding pad of the terminal block.
 2. The opticalmodule according to claim 1, wherein the laser diode submount has athickness of at least about 150 μm and at most about 350 μm.
 3. Theoptical module according to claim 1, further comprising: a flexiblecable being provided with the photodiode array and being arranged toallow optical signals, emitted from the transmitter group of the laserdiode array and from the receiver group of the fiber array, to passthrough without being attenuated; and an mechanical transfer ferrulehaving plural optical fibers which are divided to at least a transmittergroup and a receiver group and which are provided between the laserdiode array and the photodiode array, the each of the plural opticalfibers of the transmitter group of the fiber array, the each of theplural laser diodes of the transmitter group, each of the plural opticalfibers of the transmitter group of the mechanical transfer ferrule andthe each of the plural photodiodes of the monitor group being opticallyaligned along an optical axis direction of transmitter groups,respectively, and the each of the plural optical fibers of the receivergroup of the fiber array, each of the plural optical fibers of thereceiver group of the mechanical transfer ferrule and the each of theplural photodiodes of the receiver group being optically aligned alongan optical axis direction of receiver groups, respectively.
 4. Theoptical module according to claim 3, wherein the laser diode array isprovided with a laser diode lead wire, and the flexible cable isprovided with a shield metal layer on one side and a trace photodiode onan opposite side to the side with the shield metal layer.